EP3461565B1 - Separator - Google Patents

Description

The invention relates to a sifter according to the features of the preamble of claim 1.

The DE 38 23 380 C2 discloses such a sifter with a spreading plate onto which the material to be treated is placed centrally. Impact elements on the top and impact elements projecting radially outwards are attached rigidly or freely swinging below the outer edge around the circumference of the spreading plate. The spreading plate is driven independently of the rod basket. A feed cone is arranged in the centre of the spreading plate, which has the task of redirecting the falling feed material onto the spreading plate. Due to the centrifugal forces, the feed material slides to the edge of the spreading plate, at the same time giving the feed material a movement component in the direction of rotation of the spreading plate. At the edge of the spreading plate, the feed material hits the impact elements arranged on the spreading plate, so that the aggregates are crushed at this point.

After falling from the spreading disc, the particles of the feed material hit further outward-protruding impact elements of the spreading disc.

Impact elements can also be attached to the periphery of the rod basket. By means of guide plates arranged on the inside of the sifter housing above the sifting zone between the rod basket and the guide vane ring, the material is concentrated and guided into the impact circle of the impact elements of the rod basket. Despite various measures, deagglomeration is not satisfactory.

The DE 43 02 857 A1 discloses a cleaning device for cleaning a grain mixture, which has a spreader to which both a hood and a truncated cone are attached, which in turn carries a cone. Impact elements are not provided.

The WO 2014/124899 A1 describes a classifier that has internals in the classifying zone between the air guide system and the rotor basket that are intended to ensure that agglomerated feed material particles are at least partially deagglomerated. This is intended to enable more efficient classifying. The internals are arranged in such a way that they extend parallel to the rotation axis of the rotor basket or form an angle with the rotor axis. The internals, which can also be formed by end areas of the guide vanes of the air guide system, form bottlenecks or constrictions in the circumferential direction of the classifying zone.

The DE 199 61 837 A1 Also visible are installations in the form of guide flaps that protrude into the visibility zone and extend parallel to the axis of the dynamic rotor part.

The EP 1 529 568 B1 discloses a cyclone classifier in which the flow cross-section is constricted in the direction of flow of the product in front of the separation area at least at one point. For this purpose, baffles such as conical rings are used, which can be installed at several points in the classifying zone.

The FR 2597766 A1 discloses a classifier having vertical guide plates and a classifier wheel, the classifier blades and adjustment means for adjusting a Distance S between the sifter blades and the adjustment means. A sifting space is formed between the blades and the adjustment means.

The US 6 276 534 B1 discloses a classifier having a classifier wheel with inclined vanes between plates. The plates are extended radially outward beyond a vane arrangement by inclined ring sections. These sections enclose, together with the vane arrangement, an annular space, which is referred to as the classifying space. This classifying space has a radially outward opening.

The EP 2 204 240 A1 discloses a two-stage classifier having a stationary classifier and a rotating classifier. The classifier is arranged above a mill. Dried hot air is fed to the mill, creating an ascending gas particle stream that is introduced into the classifying zone between the housing wall and the stationary classifier. Some of the particles hit the stationary lamellae, so that these particles are deflected outwards. The remaining gas particle mixture hits the space between the stationary classifier and the rotating classifier, where a second classifying takes place.

The EP 0 442 788 A2 discloses a classifier having a rotor equipped with a large number of blades evenly distributed around its circumference. The rotor is surrounded by a circular row of vertical guide vanes arranged at equal distances around the rotor. A gas particle stream flows through this guide vane ring. The space between the blades and the rotor serves as the classifying space.

The EN 38 08 022 A1 discloses a vertical axis fan having an outer vane ring in a housing for supplying a fan coming from below. Gas particle flow to a viewing space enclosed by the guide vane ring.

It is an object of the invention to provide a classifier whose separation efficiency is higher than that of classifiers of the prior art.

verstanden, wobei x₂₅ und x₇₅ die Partikelgrößen der Partikel bezeichnen, deren Anteil 25 % bzw. 75 % beträgt.The term selectivity or selectivity degree refers to the ratio $\mathrm{K}=\frac{X_{25}}{{\mathrm{<figure-callout\; id="75"\; label="X"\; filenames="imgf0008.png,imgf0009.png"\; state="\{\{state\}\}">X</figure-callout>}}_{75}}$

where x ₂₅ and x ₇₅ denote the particle sizes of the particles whose proportion is 25% and 75%, respectively.

This object is achieved with a sifter according to the features of claim 1.

The classifier has a classifier wheel with classifier wheel blades and an air guide system with guide vanes for supplying classifying air, wherein an annular classifying space is arranged between the classifier wheel and the air guide system.

Such sifters are also called deflector wheel sifters.

The guide vanes are guide plates that protrude into the viewing space and extend in a vertical direction.

Because a feed cone is preferably arranged stationary on the housing, the particles of the feed material and in particular the agglomerates of the feed material have only a vertical and a radial movement component.

When the agglomerates slide down from the feed cone, they are caught and broken up by the dispersing blades of the dispersing plate rotating under the feed cone. The dispersing blades are arranged on the top of the dispersing plate and distributed around the circumference of the dispersing plate.

Preferably, four to twenty dispersing blades are provided. The lower the angular velocity ω of the dispersing plate, the greater the number of dispersing blades should be selected.

The impact effect of the dispersing blades is significantly greater than with the state of the art because the agglomerates do not yet have a movement component in the direction of rotation of the dispersing plate when they hit the dispersing blades. The separation efficiency of the classifier is significantly improved because not only is a significantly larger amount of the agglomerates deagglomerated, but the agglomerates are also almost completely broken down into their original individual particles.

Preferably, the feed cone has an opening angle β of 45° ≤ β ≤ 90°. This is a pointed cone, which has the advantage that the slope of the cone surface is large and the particles of the feed material are only slightly slowed down in their vertical movement before they hit the dispersing blades.

Preferably, the feed cone has a radius R ₁ at its edge, for which 0.5 x R ₂ < R ₁ < R ₂ applies, where R ₂ is the radius of the dispersing plate. If this relationship is observed, it is ensured that the edge of the feed cone extends as far as possible to the edge of the dispersing plate and thus the particles of the feed material are distributed to an area of the dispersing plate and the dispersing blades, which has a correspondingly high path speed v.

The impulse p = mxv acting on the agglomerates is greater the greater the path speed v. It is therefore advantageous to choose the radius R ₂ of the dispersing plate as large as possible, because then the radius R ₁ of the cone edge can also be chosen to be large within the range 0.5 x R ₂ to R _2. The path speed v at the radially outer end of the dispersing blades is preferably in the range from 40 m/s to 150 m/s, in particular in the range from 80 m/s to 150 m/s.

On the other hand, R ₁ must not be chosen too large so that the agglomerates falling from the feed cone do not shoot over the edge of the dispersing plate due to their radial velocity. It is therefore preferable to choose R ₁ < 0.9 x R ₂ , in particular R ₁ < 0.8 x R ₂ .

Preferably, the radius R ₃ of the inner circumference of the dispersing blades is R ₃ ≤ R ₁ . The inner circumference of the dispersing blades refers to the circle on which the inner surfaces of the dispersing blades pointing radially towards the center of the dispersing plate lie.

This ensures that the feed cone and its cone edge also extend into the area of the dispersing blades, so that the particles and thus also the agglomerates are first caught by the dispersing blades when they fall from the feed cone, before they hit the top of the dispersing plate.

Preferably, the distance A ₁ between the edge of the feed cone and the dispersing blades of the dispersing plate is 0 < A ₁ ≤ 30 mm and is particularly preferably 5 mm to 30 mm, in particular 5 mm to 25 mm. The The advantage of a small distance A ₁ is that the agglomerates of the feed material are captured and broken up by the dispersing blades immediately after leaving the feed cone.

Preferably, each dispersing blade has a dispersing surface that is arranged perpendicular to the direction of rotation of the dispersing plate. This has the advantage that maximum force is applied to the impacting agglomerates of the feed material.

Preferably, the dispersing blades are plates that protrude from the top of the dispersing plate and extend in radial directions.

Preferably, a baffle ring is provided on the housing, which has baffle elements distributed over the circumference and protruding in the direction of the dispersing plate. The baffle ring is preferably arranged in a fixed position on the housing. Preferably, 24 or more than 24 baffle elements are provided.

The particles of the feed material, which are thrown outwards by the impact ring due to centrifugal forces, not only hit the impact ring, but also the impact elements due to their movement component in the direction of rotation of the turntable. The advantage of the impact ring with the impact elements is that agglomerates, which may not yet have been completely broken down into individual particles by the dispersing blades of the dispersing plate, can be effectively broken down in this second stage of dispersion. This further improves deagglomeration.

The distance A ₂ between the impact elements and the dispersing plate is preferably 0 < A ₂ ≤ 30 mm, in particular 10 mm ≤ A ₂ ≤ 30 mm.

The impact elements are designed and arranged in such a way that they are at least opposite the dispersing blades. This means that the vertical extension of the impact elements is so large that it corresponds at least to the height of the dispersing blades. This ensures that as many particles of the feed material as possible that leave the dispersing plate are captured by the impact elements.

Preferably, the dispersing plate is attached to the classifier wheel. The advantage is that the dispersing plate does not require its own drive and is driven by the classifier wheel. The dispersing plate therefore has the same angular speed as the classifier wheel.

The rotating classifier wheel creates a circular flow in the classifying chamber, whereby the feed material is carried radially outwards due to centrifugal force. At the same time, the air introduced by the air guidance system imparts a movement component to the particles of the feed material in the direction of the classifier wheel.

It has been shown that the feed material, especially the deagglomerated feed material, tends to form strands in front of and in the classifying area, which impair the classification.

Streaks are understood to be an accumulation of particles in a gas flow that forms as a result of separation, e.g. due to the effect of gravity and centrifugal force. Streaks are caused by the gas exceeding its carrying capacity for the solid particles. The streaks therefore also contain smaller particles that would otherwise get into the fine material with the air flow if the solids load was low.

The guide plates protruding into the screening area cause the strands to be loosened in a targeted manner, enabling improved separation of the finest particles in particular without affecting the rest of the separation.

The guide plates extending into the classifying chamber not only break up the strands, but also give the particles of the feed material an additional movement component in the direction of the classifying wheel.

These measures improve the separating power of the classifier.

Preferably, the air guidance system comprises air windows, wherein a guide plate is arranged on at least one edge of the air windows.

The air guidance system preferably has an annular wall in which the air windows are arranged. The air flowing in through the air windows is deflected by the baffles, thereby influencing the flow into the viewing area.

The guide plates thus fulfil two tasks. Both the particles of the feed material and the incoming classifying air are influenced in the desired manner. Both flows can be specifically adjusted using the angle of attack γ of the guide plates. The angle of attack γ is spanned between the guide plates in the flow direction of the particle-air mixture in the classifying chamber and the inner radius R _L of the air guidance system. The angles γ are preferably the same for all guide plates.

Preferably, the baffles are arranged on the opposite edges of the air windows. Each air window therefore has two baffles, which allows the incoming air flow to be directed even more precisely.

The ends of the baffles are preferably spaced apart, i.e. the ends of the baffles preferably do not touch each other.

Preferably, the two baffles arranged on each air window are aligned parallel to each other. These baffle pairs form an air channel that preferably has a constant width.

Preferably, the guide plates with the radius R _L of the air guidance system have an angle of attack γ which is in the range of 30° to 60°, particularly preferably in the range of 40° to 50°.

The guide plates are preferably rectangular, flat guide elements.

The guide vanes are curved in the direction of the classifier wheel. The angle of attack γ of the curved guide vane is spanned between the tangent T in the middle of the outer surface of the guide vane and the inner radius R _L of the air guidance system in the flow direction of the particle air stream. The flow direction of the particle air stream is defined by the direction of rotation of the classifier wheel. The curved design of the guide vanes has the advantage that the particle air stream is directed even more effectively onto the classifier wheel.

Preferably, the guide vanes have a single radius of curvature R ₄ .

According to a further embodiment, it is provided that the guide plates are curved such that the radius of curvature R ₄ decreases in the direction of the classifier wheel.

The radius of curvature is preferably 5 mm ≤ R ₄ ≤ 2000 mm.

According to a further embodiment, it is provided that the guide plates are curved such that the radius of curvature R ₄ decreases in the direction of the classifier wheel.

The radius of curvature is preferably 5 mm ≤ R ₄ ≤ 2000 mm.

Preferably, the air guidance system has at least one conical ring with a particle guidance element protruding into the viewing space and having a first conical surface.

The particle air flow not only has a horizontal movement component, but also a vertical movement component due to gravity. The flow cross-section of the classifying chamber in the vertical direction of movement is constricted by the cone ring, whereby the particle air flow is diverted towards the classifier wheel by the conical surface of the particle guide element. This measure also contributes to improving the separation accuracy of the classifier.

Preferably, the conical surface is arranged on the upper side of the particle guide element and forms an angle α with a vertical axis Lv of 10° < α < 90°, particularly preferably 20° < α < 80°.

Preferably, the distance A ₄ between the inner circumference of the air guide system and the outer circumference of the sifter wheel is A ₄ = ½ • Ds (V -1), where V = D _L /D _S with 1.01 ≤ V≤ 1.2 and Ds is the outer diameter of the sifter wheel and D _{L is} the inner diameter of the air guide system. It has been shown that the classification and separation of the residual fine dust can be further improved if certain limit values are observed for this distance A ₄ , which describes the width of the sifting area, which are determined by the ratio V = D _L /D _S can be defined. Preferably, the ratio V of the diameters D _L /D _S is 1.05 ≤ V < 1.1.

Preferably, the distance A ₃ between the inner edge of the particle guide elements and/or the ends of the guide plates and the inner circumference of the classifier wheel is 0.005 x A ₄ ≤ A3 ≤ 0.5 x A ₄ .

The air guidance system preferably has at least one circumferential horizontal air slot. This horizontal air slot can extend partially or over the entire circumference of the air guidance system. This results in higher radial velocities of the classifier air of up to 30 m/s, with which the feed material is guided to the classifier wheel.

Figur 1

einen Sichter im Vertikalschnitt,

Figur 2

einen Vertikalschnitt durch den perspektivisch dargestellten oberen Bereich des Sichters,

Figur 3

eine Draufsicht auf den Sichter,

Figur 4

einen Vertikalschnitt durch Kegel und Dispergierteller des Sichters gemäß der Figur 1,

Figur 5

einen Ausschnitt aus Figur 4 in vergrößerter Darstellung,

Figur 6

einen Horizontalschnitt durch ein Sichterrad und ein Luftleitsystem gemäß einer Ausführungsform,

Figur 7

eine perspektivische Darstellung eines Luftleitsystems gemäß einer weiteren Ausführungsform,

Figur 8a

die Draufsicht auf das in Figur 7 gezeigte Luftleitsystem mit eingezeichnetem Sichterrad,

Figuren 8b,c

die Draufsicht auf ein Luftleitsystem mit Sichterrad gemäß zwei Ausführungsformen mit gekrümmten Leitblechen,

Figur 9

einen vergrößerten Ausschnitt aus Figur 8a,

Figur 10

eine weitere Ausführungsform eines Luftleitsystems mit Sichterrad in Draufsicht,

Figur 11

einen Schnitt durch ein Luftleitsystem gemäß einer weiteren Ausführungsform mit einem Konusring,

Figur 12

einen Schnitt durch einen der in Figur 11 gezeigten Konusringe,

Figur 13

einen vergrößerten Vertikalschnitt durch das Luftleitsystem und einem dazugehörigen Sichterrad, und

Figur 14

ein Diagramm der Summenverteilungskurven Q₃ zur Erläuterung der Ausbeute und Trennschärfe des Sichters.

Exemplary embodiments of the invention are explained in more detail below with reference to the schematic drawings. They show:

Figure 1

a sifter in vertical section,

Figure 2

a vertical section through the perspective view of the upper part of the sifter,

Figure 3

a top view of the sifter,

Figure 4

a vertical section through the cone and dispersing plate of the classifier according to the Figure 1 ,

Figure 5

an excerpt from Figure 4 in enlarged view,

Figure 6

a horizontal section through a classifier wheel and an air guidance system according to an embodiment,

Figure 7

a perspective view of an air guidance system according to another embodiment,

Figure 8a

the top view of the Figure 7 shown air guidance system with drawn classifier wheel,

Figures 8b,c

the top view of an air guidance system with classifier wheel according to two embodiments with curved guide vanes,

Figure 9

an enlarged section of Figure 8a ,

Figure 10

another embodiment of an air guidance system with classifier wheel in plan view,

Figure 11

a section through an air guidance system according to another embodiment with a conical ring,

Figure 12

a section through one of the Figure 11 shown cone rings,

Figure 13

an enlarged vertical section through the air guidance system and an associated sifter wheel, and

Figure 14

a diagram of the cumulative distribution curves Q ₃ to explain the yield and selectivity of the classifier.

In the Figure 1 a sifter 1 is shown in vertical section. The sifter 1 has a housing 2 which has a filling pipe 6 and is divided into an upper housing part 3 and a lower housing part 5. In the upper housing part 3, which is essentially cylindrical, there is a classifier wheel 60 with classifier wheel blades 62 and an air guide system 70 with three guide vane rings 72. The classifying chamber 18 is located between the classifier wheel 80 and the air guide system 70. A dispersing plate 30 is attached to the classifier wheel 60 and is thereby driven by the classifier wheel 60.

The dispersing plate 30 has on its upper side 31 (see also Figure 2 ) has dispersing blades 40 in the edge region, which consist of essentially rectangular metal plates that protrude upwards from the upper side 31 of the dispersing plate 30 and extend to the edge 33 of the dispersing plate 30. A feed cone 20 is fixedly attached to the housing 2 above the dispersing plate.

The upper housing part 3 has a sifter cover 4 in which the filling pipe 6 with the filling opening 7 for the feed material is arranged. The feed material is filled into the sifter 1 through the filling pipe 6 and there hits the feed cone 20.

The drive shaft 13 for the sifter wheel 60 is arranged in the lower housing part 5 and is driven at the lower end by a drive device 12. The lower housing part 5 also has an outlet pipe with the outlet opening 9 for discharging the fine material. A suction fan 11 and the outlet 10 for the coarse material are arranged at the lower end of the conical lower housing part 5.

The Figure 2 shows a detailed section through the upper part of the housing 3.

The feed cone 20 projects with its cone tip 26 into the filling pipe 6 and is fastened there to the filling nozzle 6 by means of a fastening element 22.

The dispersing plate 30 is surrounded by an impact ring 50, which has impact elements 54 on its inner surface 52, which protrude from the inner surface 52 in the direction of the dispersing plate 30. The impact elements 54 are distributed over the inner surface 52 of the impact ring 50 and extend in the vertical direction at least over the entire height of the dispersing blades 40. A conical wall 58 adjoins the impact ring 50 at the top.

The classifier wheel 60 arranged under the dispersing plate 30 has a plurality of vertically aligned classifier wheel blades 62 and is surrounded by an air guide system 70 with a total of three guide vane rings 72.

In the Figure 3 is the top view of the Figure 1 shown sifter 1, which has two sifting air inlets 8a,b arranged tangentially on the housing part 3. A total of twenty-four impact elements 54 are arranged on the impact ring 50. The impact elements 54 are arranged at a distance from the dispersing plate 30. The dispersing plate 30 has six dispersing blades 40 on its upper side 31, some of which extend below the feed cone 20. The inner circumference of the dispersing blades 40 is marked by the dashed circular line 44 on which the inner surfaces 41 of the dispersing blades 40 lie. The corresponding radius R ₃ of the inner circumference 44 of the dispersing blades 40 is also shown, as is the radius R ₁ of the cone edge 24 of the feed cone 20.

The Figures 4 and 5 show enlarged sectional views of the upper part of the Figure 2 shown sifter 1. The feed cone 20 has an opening angle β of approximately 85°. The feed cone 20 extends into the area of the dispersing blades 40, so that the feed material 14 introduced from above through the filling pipe 6 is fed directly to the dispersing blades 40. The agglomerates in the feed material 14 are identified by the reference number 15. The agglomerates 15 as well as the other particles of the feed material 14 are first captured by the dispersing surface 46 of the dispersing blades 40 before they impact the upper side 31 of the dispersing plate 30.

Due to the centrifugal forces acting on the particles of the feed material 14, the particles are thrown in the direction of the impact ring 50, where they hit the impact elements 54. The radii R ₁ , R ₂ and R ₃ are shown, whereby it can be seen that the radius R ₃ is smaller than the radius R ₁ , whereby the radius preferably applies 0.4 x R ₂ ≤ R ₃ ≤ 0.8 x R ₂ . This ensures that the agglomerates 15 of the feed material 14 do not shoot out over the edge 33 of the dispersing plate 30 when leaving the feed cone 20 without hitting the dispersing blades 40.

This fact is illustrated in a further enlarged representation of the Figure 5 clear to see.

In the Figure 5 the distance A ₁ between the cone edge of the feed cone 20 and the upper surface 43 of the dispersing blade 40 is shown. The distance A ₂ between the edge surface 34 of the dispersing plate and the impact element 56 is also shown. The outer surface 42 of the dispersing blade 40 is set back from the edge surface 34 of the dispersing plate 30.

The impact element 54 extends below the plane in which the underside 32 of the dispersing plate 30 lies. The length Ls of the dispersing blades 40 is preferably in the range of 0.02 x R ₂ ≤ Ls ≤ 0.2 x R ₂ . The height Hs is preferably in the range of 0.01 x R ₂ ≤ Hs ≤ 0.1 x R ₂ .

In the embodiment shown here, A ₁ ≃ R ₂ /6. Preferably, A ₁ < R ₂ /2.

The height H _P of the impact elements 54 is preferably 0.03 x R ₂ ≤ Hp ≤ 0.5 x R ₂ . The width B _P of the impact element 54 is slightly less than the height Hs of the dispersing blade 40.

Representing the agglomerates, an agglomerate particle 15 is shown, which slides down the cone surface and is captured by the dispersing surface 46 and broken down into its individual particles. The resulting deagglomerated particles 16 hit the impact surface 56 of the impact element 54 and are further deagglomerated there.

In the Figure 6 1 shows the top view of a classifier wheel 60 with classifier wheel blades 62 and an associated air guide system 70 with air guide vanes 73. The guide vane ring 72 of the air guide system 70 has an inner diameter D _L . The outer diameter of the classifier wheel 60 is indicated by Ds. This results in a width A ₄ of the annular classifying space 18.

In the Figure 7 A further embodiment of the air guiding system 70 is shown. The air guiding system 70 has two rings 79, between which a ring wall 71 with air windows 74 is arranged. The air windows 74 are arranged evenly over the entire circumference of the ring wall 71. In the embodiment shown here, these are rectangular air windows 74, each of which has air guiding vanes 73 in the form of guide plates 76 on the left edge 75. These guide plates 76 are arranged so as to be pivotable about an axis L _SA , so that the angle of attack γ, which in the Figure 9 is marked, can be adjusted specifically.

In the Figure 9 In the screening chamber 18, the arrow P ₂ indicates the flow direction of the particle air stream, which is generated by the rotation of the screening wheel 60 in the direction of the arrow P _1. The angle γ is spanned between the inner radius R _L of the air guidance system 70 and the guide plate 76.

In the Figure 8a is the air guidance system 70 of the Figure 7 shown combined with a classifier wheel 60. P ₁ indicates the direction of rotation of the classifier wheel 60. P ₂ indicates the flow direction of the particle air stream.

In the Figure 8b A further embodiment is shown in which the guide plates 76 are curved. The guide plates 76 have a uniform radius of curvature R ₄ and are arranged curved in the direction of the separator wheel. The angle of attack γ is characterized by the tangent T through the center of the guide plate 76 and the inner radius of the air guidance system 70.

In the Figure 8c A further embodiment is shown in which the guide plates 76 do not have a uniform radius of curvature, but rather have a radius of curvature that decreases from the outside to the inside. The radius of curvature R ₆ at the end of the curved guide plate 76 is smaller than the radius of curvature R ₅ .

In the Figure 10 a further embodiment of the air guidance system 70 is shown, in which guide plates 77a, 77b are arranged opposite each other on both edges 75 of the air windows 74. The air inflow is indicated by the arrows shown. While the guide plates 77a are short, the guide plates 77b are longer. In the embodiment shown here, the adjacent guide plates 77a and 77b of two windows 74 are each aligned parallel, so that an air channel with a constant width is created. The ends 77c of the guide plates 77a, 77b do not touch each other and are arranged at a distance from each other.

In the Figure 11 a further embodiment of the air guiding system 70 is shown, in which three guide vane rings 72 are arranged one above the other, with a conical ring between the rings 79 of adjacent guide vane rings 72 80 is arranged. In addition, a horizontal ring-shaped air slot 78 is provided in this air guidance system 70, through which the viewing air is introduced into the viewing space 18.

In the Figure 12 a conical ring 80 is shown in section. The conical ring 80 has a particle guide element 82 with a first conical surface 84 on the upper side and a second conical surface 86 on the lower side. The angle of inclination of the surface 84 to a vertical axis Lv is marked with α.

In the Figure 13 the air guidance system 70 is shown together with a classifier wheel 60, so that it can be seen that the particle guide elements 82 protrude into the classifying space 18. The distance A ₃ from the inner edge 88 of the particle guide elements 84 to the classifier wheel is marked with A _3. Furthermore, the diameters D _L and Ds as well as the distance A ₄ between the air guidance system 70 and the classifier wheel 60 are shown.

Tests were carried out using a mineral powder as the feed material. The particle size of the feed material was < 50 µm, with 70% of the particles having a size of < 10 µm (d ₇₀ = 10 µm). 20% of the particles had a particle size of < 3 µm.

This powder was classified in a conventional classifier without the inventive feed cone and without the inventive dispersing disk. The corresponding cumulative distribution curve I is shown in the Figure 14 in which the cumulative distribution Q ₃ (x) is plotted as a function of the grain size x, where Q ₃ (x) = (mass of particles ≤ particle size x) / (total mass of all particles) (see " "Fine Grinding System with Impact Classifier Mill and Cyclone Classifier" by Giersemehl and Plihal, Power Handling and Processing Vol. 11, No. 3, July/Sept. 1999 ). The discrimination power κ is κ = 0.51.

The same powder was sifted in a classifier according to the invention with the feed cone according to the invention, dispersing plate with dispersing blades and an impact ring according to the Figures 1 to 5 and an air guidance system in accordance with Figure 6 classified.

The cumulative distribution curve II obtained with the classifier according to the invention is also shown in the Figure 14 Curve II differs from curve I by an improved separation efficiency with κ = 0.56 and an increase in the yield of particles with particle sizes < 3 µm. The yield for this particle range was 7.3% with the prior art (curve I) and 11.3% with the classifier according to the invention (curve II). This is an increase in yield of 54.8%.

It has been shown that the classifier according to the invention leads to a significantly better deagglomeration, which is reflected in the difference between the cumulative distribution curves I and II.

When using a separator according to the invention, which additionally has the air guidance system according to Figures 8 and 11 the degree of separation κ for the same feed material can be increased up to κ = 0.7.

List of reference symbols

1

Sifter

2

Housing

3

upper housing part

4

Sifter lid

5

lower housing part

6

Filling pipe

7

Filling opening feed material

8a,b

Visual air supply

9

Outlet opening fines

10

Outlet opening coarse material

11

Suction fan

12

Drive system

13

drive shaft

14

Feed material

15

agglomerate

16

deagglomerated particles

18

Viewing space

20

Feed cone

22

Fastener

24

Cone edge

26

Cone tip

30

Dispersing plate

31

Top

32

bottom

33

edge

34

Edge area

40

Dispersing blade

41

Inner surface

42

Exterior surface

43

Top surface

44

Inner circumference

46

Dispersing area

50

Impact ring

52

Inner surface of the impact ring

54

Impact element

56

Impact surface

58

conical wall

60

Classifier wheel

62

Classifier wheel blade

70

Air guidance system

71

Ring wall

72

Guide vane ring

73

Guide vanes

74

Air window

75

Edge of the air window

76

Baffle

77a,b

Baffle

77c

Baffle end

78

Air slot

79

ring

80

Cone ring

82

Particle guide element

84

first conical surface

86

second conical surface

88

Inner edge

BP

Width impact element

HP

Height impact element

Hs

Height of dispersing blade

Ls

Length of dispersing blade

α

Cone angle of the cone ring

β

Opening angle of the feed cone

γ

Angle of attack of the guide plate

DL

Inner diameter of the air duct system

Ds

Outside diameter of the classifier wheel

LSA

vertical swivel axis

Lv

vertical axis

T

tangent

RL

Inner radius of the air duct system

R1

Radius of the cone edge

R2

Radius of the dispersing plate

R3

Radius of the inner circumference of the dispersing blades

R4

Radius of curvature

R5

Radius of curvature

R6

Radius of curvature

A1

Distance feed cone edge - top surface of dispersing blade

A2

Distance between inner surface of impact element and edge surface of dispersing plate

A3

Distance end of guide plate - outer circumference of classifier wheel

A4

Distance between inner circumference of air guide ring and outer circumference of classifier wheel

P1

Rotation direction of the classifier wheel

P2

Flow direction of the particle air flow

Claims (14)

1. A separator with

   - a separator wheel (60) having separator wheel paddles (62) and an air guidance system (70) having guide vanes (73) for the supply of separating air, while an annular separating space (18) is arranged between the separator wheel (60) and the air guidance system (70),
   wherein

   the guide vanes (73) are guide plates (76, 77a, b) protruding into the separating space (18) and extending in the vertical direction,

   characterized in that

   the guide plates (76, 77a, b) are curved in the direction of the separator wheel (60).
2. The separator as claimed in claim 1, characterized in that a dispersing plate (30) is fastened to the separator wheel (40).
3. The separator as claimed in one of claims 1 or 2, characterized in that the air guidance system (70) has air windows (74) and a guide plate (76) is arranged on at least one edge (75) of the air windows (74).
4. The separator as claimed in claim 3, characterized in that the guide plates (77a, b) are arranged on opposite edges (75) of the air windows (74).
5. The separator as claimed in claim 4, characterized in that the guide plates (77a, b) are arranged between two respective air windows (74) such that their ends (77c) converge on each other.
6. The separator as claimed in one of claims 4 or 5, characterized in that the two respective guide plates (77a, b) which are arranged at each air window (74) are oriented parallel to each other.
7. The separator as claimed in one of claims 1 to 6, characterized in that the guide plates (76, 77a, b) make an angle of attack γ with the radius R_L of the air guidance system (70) of 30° ≤ γ ≤ 60°.
8. The separator as claimed in one of claims 1 to 5 or 7, characterized in that the guide plates (76, 77a, b) have a single radius of curvature R₄.
9. The separator as claimed in one of claims 1 to 5 or 7, characterized in that the guide plates (76, 77a, b) are curved such that the radius of curvature R₄ decreases in the direction of the separator wheel (60).
10. The separator as claimed in one of claims 8 or 9, characterized in that the radius of curvature R₄ is 5 mm ≤ R₄ ≤ 2000 mm.
11. The separator as claimed in one of claims 1 to 10, characterized in that the air guidance system (70) has at least one cone ring (80) with a particle guide element (82) protruding into the separating space (18) and having a first conical surface (84).
12. The separator as claimed in claim 11, characterized in that the first conical surface (84) is arranged on the upper face of the particle guide element (82) and forms an angle α with a vertical axis Lv of 10° < α < 90°.
13. The separator as claimed in one of claims 1 to 12, characterized in that the distance A₄ between the inner circumference of the air guidance system (70) and the outer circumference of the separator wheel (60) is $${\mathrm{A}}_4=\mathrm{1/2}\cdot {\mathrm{D}}_{\mathrm{S}}\left(\mathrm{V}-1\right)$$

    

    where V = D_L/D_S with 1.01 ≤ V ≤ 1.2 and Ds denotes the outer diameter of the separator wheel (60) and D_L the inner diameter of the air guidance system (70).
14. The separator as claimed in one of claims 1 to 13, characterized in that the air guidance system (70) has at least one circumferential horizontal air slot (78).

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